Coronavirus: looking for the best exit strategy

There are three main strategies to get out of the coronavirus lockdown, but each exposes us to the risk of a second wave of infections and further blocks if things do not go as planned.

Bans, curfews and limitations on daily life for half the planet's population have become the new normal. But as we adjust to these coronavirus measures, what prospect is there of returning to the “old normal”? What is the exit strategy from the coronavirus?

If you are hoping for a return to your old life, I have good news and bad news: it will happen, but I don't think soon. “It is absolutely true that government consultants and researchers are considering the question of a coronavirus exit strategy”. The epidemiologist says it Mark Woolhouse from the University of Edinburgh, UK. But what will be the exit strategies of the different nations? The lack of coordination at an international level could lead to patchy contagion problems.

The lockdowns that many nations are enduring are a short-term strategy to reduce the average number of infections and stop their exponential growth. With a term you've been hearing for weeks, "flattening the curve." The approach is aimed at preventing hospitals from being overwhelmed, reducing the number of deaths and buying time to increase beds, understand the virus and find new treatments.

However, blocking is not a long-term strategy.

 “We want to get out of lockdown because of all the damage it is doing, economically and psychologically,” he says Woolhouse. But removing the restrictions can cause the infection rate to grow exponentially again.

Developing an exit strategy, therefore, becomes a question of determining the best time to eliminate the restrictions and the actions to be taken to keep a return of infections under control.

So how do we emerge from lockdown without sparking a dangerous second wave of infections among people who weren't exposed to the virus the first time? A second wave like this is “highly likely,” he says Susy Hota, Medical Director of the Infection Prevention and Control Program at the University Health Network of Toronto, Canada.

Sure, each second wave is likely to be less severe than the first, Woolhouse says. 

“With any new emerging virus, the first wave is always the worst. Then it becomes much more manageable.” For example, since the Zika epidemic of 2015 to 2016, subsequent outbreaks have tended to fade due to the detection and control measures currently in place, as well as a greater degree of immunization in the population.

The exit strategy must therefore include a plan to manage a second wave. There are three ways to do this: we can call them upkeep, build, and shield.

Retention

The maintenance strategy is long-term: blocking until the rate of new infections approaches zero. Even if waiting for an infection rate close to zero risks imposing a block for a long time.

In phase two, when the rate falls, off the block and aggressive containment strategy. This means diagnosing second wave cases as quickly as possible, isolating them, tracing their contacts, and isolating them too to cut off all new transmission lines.

This requires developing a far better ability to trace contacts than we do today.

Construction

The second strategy, building, buys health services time to recover from the first wave and have the ability to deal with the second. In wealthier nations, the limiting factors of health services are beds, equipment, and intensive care personnel. So this strategy involves a block long enough to allow for these 3 factors. In phase two, gradually release the restrictions and deal with the second wave, hopefully with a much lower death rate. But how much ICU capacity does it take to achieve this? It's a hard question. And one wrong answer can cost many, too many lives.

Shield

Option three, the shield, is to abruptly end the lockdown, broadly protecting those who are arguably most vulnerable to the virus. This means finding ways to ensure the safety of elderly people, immunosuppressed people and those suffering from other diseases. To succeed, widespread community screening is needed to find out who is contagious (especially the asymptomatic) and ensure that they do not come into contact with vulnerable people.

Another element of this exit strategy from the coronavirus is the development of antibody tests to identify medical personnel and health workers who have already recovered and therefore with less risk of infecting others.

The effect would be to reduce critical cases and deaths. Reduce the pressure on hospitals, while allowing the famous “herd immunity” to be achieved. Covid-19 could continue to affect (and rarely kill) young people without other health conditions. However, protection would reduce the number of cases among the most vulnerable people, allowing health services to treat them better.

Which exit strategy is more valid?

The choice between these three strategies depends largely on some unknowns. In particular, the speed with which a population exceeds the threshold of recovered people necessary for herd immunity. It is the moment when enough people have acquired antibodies against the virus and prevent it from circulating rapidly in the population.

We still don't know if recovery from covid-19 make you immune to the virus in the long term. But even if immunity is only temporary, when enough people recover, herd immunity will slow or stop its spread for a while.

If none are valid?

Each coronavirus exit strategy among these three may also have to be abandoned or suspended if the second wave gets out of hand, which could mean a repeated cycle of lockdowns, openings, new lockdowns. It is certainly possible that once the lock is released it may need to be reintroduced.

If we are successful, we will have crushed the contagion curve but then we must not suddenly return to our normal way of life. It would be quite dangerous.

If we stop, all our efforts will be wasted and we could potentially see a second peak. 

We need to maintain the measures and then gradually adjust some of them, to cautiously lead us towards a new normal.

Chance of success for any coronavirus exit strategy? Unknown. 

Un recent study on how the epidemic in the United Kingdom could unfold in the next 18 months concluded that “the inherent randomness of social processes can lead to a wide range of possible outcomes.” A very elegant formula to say that not enough is yet known.

“Models are based on important assumptions, and often these assumptions are wrong,” says the virologist Jonathan Ball from the University of Nottingham, UK. “Although such models can give an idea of ​​what might happen, they cannot tell us what will happen and the sooner we understand this, the better”. There is no substitute for field research, she says.

Learn from China

For this, many are looking to China, the initial center of the pandemic. “China was the first nation to enforce the blockade,” says the epidemiologist Caroline Walters at Imperial College London. “So because they're a little bit ahead, I think everyone looks at how they're handling the situation.”

China has basically followed the tightening strategy, imposing strict social distancing on Wuhan in Hubei Province from 23st January, the (official) beginning of the epidemic. The 23 March, for the first time since the beginning of the epidemic, five consecutive days had passed without new cases in the country. Restrictions have now been eased, including in much of Hubei, and will also be lifted in Wuhan tomorrow 8 April.

“Life hasn't gone back to normal, but they've slowly started to let people move around a little more.”Walters says. “They are no longer as stuck as they were before.”

Early signs suggest that China has somehow successfully emerged from the strict social distancing.

As a result, economic activity appears to be picking up again, according to a recent study of Imperial College London's COVID-19 response team, of which Walters is a member. 

The team obtained a set of motion level data in major cities in each mainland China province between January 1 and March 17, acquired by Chinese search engine Baidu's phone location-based services.

The researchers found that levels of movement closely correlated with the number of new cases in the first analysis period. People were spreading the virus in their daily lives. But once containment measures were enforced and then loosened, that correlation disappeared.

“Transmission has remained low, despite people being able to move,” Walters says. “We are seeing some people able to return to normal economic activity without the virus returning to the same level of transmission.”

All we are looking at is correlation, not causation.

We cannot say directly “this caused this”. The findings cannot rule out further outbreaks. China's service and manufacturing sectors reported a return to growth last month after a major slump in February. China's National Bureau of Statistics says more than half of businesses have resumed work, although it warns that China's economy is not yet back to normal.

Reports are also emerging that some recently reopened businesses, such as cinemas and bars, are suddenly shut down again. Authorities don't explain these closures, second a Washington Post report . The possibility of a new round of infections remains relatively high. Epidemiologists claim that if a second wave hits China, it will be evident by the end of this month.

So can China serve as a model for the rest of the world? 

To a certain extent yes, but the coronavirus exit strategy will have to be adapted to local conditions. Not all countries will have the capacity to carry out testing or contact tracing, for example.

The European Union has said that it is working on a coordinated exit strategy , but there are still no details and today's meeting between the ministers of the various European states does not bode well. 

Until now, exit strategies have been managed nationally or transnationally rather than internationally, despite the outbreak being a pandemic.

The WHO said there is no global exit strategy yet, saying the organization is currently focusing on the response to the virus.

Whatever coronavirus exit strategy is put in place, it is likely that we will eventually return to something that resembles our old lives. 

“We have to find a way to live with this virus and still function more or less as usual”, he claims Woolhouse. Maybe we will live with this virus forever, but certainly for the foreseeable future. 

So the long-term strategy is “how do we live with covid-19?

Within a year or so, vaccines could become part of the answer and even improved treatments and some level of herd immunity will play a role in the global exit strategy from the coronavirus.

“I think we'll go back to our old lives,” Walters says. “Pandemics have happened before. These measures are not eternal. They were introduced to achieve a certain goal, which is flattening the curve to protect our healthcare system. We don't know exactly when it will end. But it will end. “